udev: move util_resolve_subsys_kernel() to udev-util.c

1 files changed, 65 insertions, 0 deletions

diff --git a/src/shared/udev-util.c b/src/shared/udev-util.c
index d03e4bbe6f..5a506887e7 100644
--- a/src/shared/udev-util.c
+++ b/src/shared/udev-util.c
@@ -16,6 +16,7 @@
 #include "signal-util.h"
 #include "string-table.h"
 #include "string-util.h"
+#include "strxcpyx.h"
 #include "udev-util.h"
 #include "utf8.h"
 
@@ -471,3 +472,67 @@ size_t udev_replace_chars(char *str, const char *allow) {
         }
         return replaced;
 }
+
+int udev_resolve_subsys_kernel(const char *string, char *result, size_t maxsize, bool read_value) {
+        _cleanup_(sd_device_unrefp) sd_device *dev = NULL;
+        _cleanup_free_ char *temp = NULL;
+        char *subsys, *sysname, *attr;
+        const char *val;
+        int r;
+
+        assert(string);
+        assert(result);
+
+        /* handle "[<SUBSYSTEM>/<KERNEL>]<attribute>" format */
+
+        if (string[0] != '[')
+                return -EINVAL;
+
+        temp = strdup(string);
+        if (!temp)
+                return -ENOMEM;
+
+        subsys = &temp[1];
+
+        sysname = strchr(subsys, '/');
+        if (!sysname)
+                return -EINVAL;
+        sysname[0] = '\0';
+        sysname = &sysname[1];
+
+        attr = strchr(sysname, ']');
+        if (!attr)
+                return -EINVAL;
+        attr[0] = '\0';
+        attr = &attr[1];
+        if (attr[0] == '/')
+                attr = &attr[1];
+        if (attr[0] == '\0')
+                attr = NULL;
+
+        if (read_value && !attr)
+                return -EINVAL;
+
+        r = sd_device_new_from_subsystem_sysname(&dev, subsys, sysname);
+        if (r < 0)
+                return r;
+
+        if (read_value) {
+                r = sd_device_get_sysattr_value(dev, attr, &val);
+                if (r < 0 && r != -ENOENT)
+                        return r;
+                if (r == -ENOENT)
+                        result[0] = '\0';
+                else
+                        strscpy(result, maxsize, val);
+                log_debug("value '[%s/%s]%s' is '%s'", subsys, sysname, attr, result);
+        } else {
+                r = sd_device_get_syspath(dev, &val);
+                if (r < 0)
+                        return r;
+
+                strscpyl(result, maxsize, val, attr ? "/" : NULL, attr ?: NULL, NULL);
+                log_debug("path '[%s/%s]%s' is '%s'", subsys, sysname, strempty(attr), result);
+        }
+        return 0;
+}